936 resultados para Coloration vitale
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Resumen tomado de la publicación. Monográfico titulado: economía de la educación
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Resumen basado en el de la publicación
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Resumen basado en el de la publicación
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We tested the hypothesis that cryptically colored eggs would suffer less predation than conspicuous eggs in the ground-nesting red-legged partridge, Alectoris rufa. We used A. rufa as a model species because it has a wide range of natural egg colors, the eggs are widely available from breeding farms, and nests are easily mimicked because they are scrapes containing no vegetation. The study was conducted in the spring of 2001 in forest and fallow fields of central Spain in Castilla La Mancha, Ciudad Real. We used 384 clutches of natural eggs that were white, white spotted, brown, or brown spotted. Within clutches, eggs were consistent in color and size; among clutches, color differences were distributed across habitats. Clutches were checked once after 2 wk of exposure. Cryptic coloration had a survival advantage that was dependent on the local suite of predators. Rodent predation was nonselective with respect to clutch color; however, avian predation was significantly higher for conspicuous clutches. In addition, there was an interaction of landscape and egg color for avian predation. In forest landscapes, the clutches with highest survival were brown spotted, whereas in fallow landscapes, brown and brown spotted clutches had higher survival than white and white potted clutches. Thus, both the predator suite and the landscape had significant effects on the value of cryptic egg coloration. Our study is relevant for conservationists and managers in charge of restocking programs in hunting areas. The release of other partridge species or their hybrids could result in hybridization with wild partridges, potentially leading to nonoptimal clutch pigmentation and reduced survival of the native species. We therefore recommend that local authorities, managers, and conservationists be cautious with the use of alien species and hybrids and release only autochthonous species of partridges within their natural ranges.
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Indirect and direct models of sexual selection make different predictions regarding the quantitative genetic relationships between sexual ornaments and fitness. Indirect models predict that ornaments should have a high heritability and that strong positive genetic covariance should exist between fitness and the ornament. Direct models, on the other hand, make no such assumptions about the level of genetic variance in fitness and the ornament, and are therefore likely to be more important when environmental sources of variation are large. Here we test these predictions in a wild population of the blue tit (Parus caeruleus), a species in which plumage coloration has been shown to be under sexual selection. Using 3 years of cross-fostering data from over 250 breeding attempts, we partition the covariance between parental coloration and aspects of nestling fitness into a genetic and environmental component. Contrary to indirect models of sexual selection, but in agreement with direct models, we show that variation in coloration is only weakly heritable (h(2) < 0.11), and that two components of offspring fitness-nestling size and fledgling recruitment-are strongly dependent on parental effects, rather than genetic effects. Furthermore, there was no evidence of significant positive genetic covariation between parental colour and offspring traits. Contrary to direct benefit models, however, we find little evidence that variation in colour reliably indicates the level of parental care provided by either males or females. Taken together, these results indicate that the assumptions of indirect models of sexual selection are not supported by the genetic basis of the traits reported on here.
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The continuing importance of blue denim maintains indigo as an important vat dye industrially. In this review, we examine the various methods that have been used in the past and are currently used to reduce and dissolve indigo for dyeing. We discuss recent insights into the bacterial fermentation technology, the advantages and disadvantages of the direct chemical methods that have predominated for the last century and potentially cleaner technologies of catalytic hydrogenation and electrochemistry, which are becoming increasingly important. With considerations of environmental impact high on the dyeing industry's agenda, we also discuss the developments that have led to the production of pre-reduced indigo.
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This unique book is the first of its kind to explore the diversity of interactions between insects and birds. A group of international experts enthusiastically agreed to contribute to the four sections of the book following the success of an Entomological Club Conference on Insect and Bird Interactions. The first section covers population management issues, discussing effects on birds highly relevant to the planting of large areas of GM crops, new opportunities for increasing biodiversity in farming landscapes, and the novel aspect of managing insects by exploiting birds as biological control agents. This is followed by a section discussing the effects of insecticides on bird populations, and includes a contribution from the RSPB, as well as a re-appraisal of the effects of DDT on raptors. Next, the foraging behaviour of birds on insects is discussed, with chapters also on 'warning' coloration in insects and learning by birds. The first chapter in this section is unusual in having been written by an ophthalmologist and covers colour vision in birds, more specifically ultraviolet vision in relation to insect coloration. Finally, the authors look at insects that are parasites of birds or feed on the detritus in nests, and review the ecology and evolution of the co-adaptation of insect ectoparasites with birds. Insect and Bird Interactions is unparalleled in scope and coverage and will be of interest to entomologists, ornithologists, and ecologists alike.
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L'illustration de la plupart des manuscrits de la Suite Vulgate met l'accent sur l'intervention prophétique de Merlin et sur l'accomplissement des désastres qu'il annonce au roi de Jérusalem Flualis, replaçant l'épisode dans une série de passages où Merlin fait la démonstration de ses pouvoirs surnaturels et de sa capacité à interpréter les songes. Pourtant, dans un petit groupe d'ouvrages, l'illustration se focalise sur la conversion ultime de Flualis et de sa femme, insistant sur le caractère exemplaire et édifiant d'un épisode qui propose une résolution des relations entre païens et chrétiens différente de celles habituellement mises en scène dans l'univers à coloration épique de la continuation.
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Mapania sapuaniana, a spectacular new sedge species from Lanjak Entimau, Sarawak, is described and illustrated. It is closely related to M. richardsii and M. bomeensis but differs in having broad leaves with a distinct pseudopetiole, reddish purple or maroon coloration on the underside of the leaf and petiole and an inflorescence composed of several spikes.
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A new species of cubozoan jellyfish has been discovered in shallow waters of Bonaire, Netherlands ( Dutch Caribbean). Thus far, approximately 50 sightings of the species, known commonly as the Bonaire banded box jelly, are recorded, and three specimens have been collected. Three physical encounters between humans and the species have been reported. Available evidence suggests that a serious sting is inflicted by this medusa. To increase awareness of the scientific disciplines of systematics and taxonomy, the public has been involved in naming this new species. The Bonaire banded box jelly, Tamoya ohboya, n. sp., can be distinguished from its close relatives T. haplonema from Brazil and T. sp. from the southeastern United States by differences in tentacle coloration, cnidome, and mitochondrial gene sequences. Tamoya ohboya n. sp. possesses striking dark brown to reddish-orange banded tentacles, nematocyst warts that densely cover the animal, and a deep stomach. We provide a detailed comparison of nematocyst data from Tamoya ohboya n. sp., T. haplonema from Brazil, and T. sp. from the Gulf of Mexico.
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A new species of Neotropical freshwater stingray, family Potamotrygonidae, is described from the Rio Nanay in the upper Rio Amazonas basin of Peru. Potamotrygon tigrina, n. sp., is easily distinguished from all congeners by its conspicuous dorsal disc coloration, composed of bright yellow to orange vermiculations strongly interwoven with a dark-brown to deep-black background. Additional features that in combination diagnose P. tigrina, n. sp., include the presence of a single angular cartilage, low and not closely grouped dorsal tail spines, and coloration of tail composed of relatively wide and alternating bands of creamy white and dark brown to black. Potamotrygon tigrina is closely related to Potamotrygon schroederi Fernandez-Yepez, 1958, which occurs in the Rio Negro (Brazil) and Rio Orinoco (Venezuela, Colombia). Both species are very similar in proportions and counts, and share features hypothesized to be derived within Potamotrygonidae, related to their specific angular cartilage morphology, distal tail color, dorsal tail-spine pattern, and ventral lateral-line system. To further substantiate the description of P. tigrina, n. sp., we provide a redescription of P. schroederi based on material from the Rio Negro (Brazil) and Rio Orinoco (Venezuela). Specimens from the two basins differ in number of vertebral centra and slightly in size and frequency of rosettes on dorsal disc, distinctions that presently do not warrant their specific separation. Potamotrygon tigrina is frequently commercialized in the international aquarium trade but virtually nothing is known of its biology or conservation status.
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Philodryas laticeps Werner, 1900 was previously known only from the holotype, which was believed to be lost during the World Wars. We found the holotype to be housed in the Museum fur Naturkunde, Berlin and here redescribe it and report on three additional specimens from the collections of the Instituto Butantan, Sao Paulo and Museum fur Naturkunde, Berlin. We conclude that Philodryas oligolepis Gomes, 1921 and P. affinis Muller, 1928 are junior synonyms of Philodryas laticeps Werner, 1900. All specimens share the presence of a black mucosa surrounding the larynx and trachea in the floor of the mouth and distal rows of middle sized spines disposed in a typical ""V-shaped"" configuration on the asulcate surface of the hemipenial body, two uniquely derived features absent in all other species of the genus Philodryas. Intraspecific variation of external morphology, hemipenes, and coloration are documented.
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Hemiancistrus pankimpuju, new species, and Panaque bathyphilus, new species, are described from the main channel of the upper (Maranon) and middle (Solimoes)Amazon River, respectively. Both species are diagnosed by having a nearly white body, long filamentous extensions of both simple caudal-fin rays, small eyes, absence of an iris operculum and unique combinations of morphometrics. The coloration and morphology of these species, unique within Loricariidae, are hypothesized to be apomorphies associated with life in the dark, turbid depths of the Amazon mainstem. Extreme elongation of the caudal filaments in these and a variety of other main channel catfishes is hypothesized to have a mechanosensory function associated with predator detection.
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A new species of the tree toad genus Dendrophryniscus is described from a rainforest habitat at Parque Nacional de Serra das Lontras, municipality of Arataca, southern Bahia, Brazil. Dendrophryniscus oreites sp. nov. is related to the Atlantic forest brevipollicatus group by hand morphology, skin texture, ventral coloration and bromelicolous habits. The new species differs from related species by having a larger size, warty skin, inner finger reduced with presence of a dark nuptial pad in males, and a yellowish coloration with discrete dorsal pattern. This discovery highlights the importance of southern Bahia in terms of conservation, and for our understanding of the evolution of the frog diversity within the Atlantic Rainforest.
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In the last ten to fifteen years, there has been a predominant belief that the linear-supralinear-sublinear behaviour of the TL response of alkali halides to the radiation dose necessarily occurs in the heating stage for TL reading. It is based on the assumption that coloration in these crystals grows linear-sublinearly with the dose during irradiation. Since both colour centre and TL centre are based on the same point defects the TL response should also grow linear-sublinearly with dose. In 1950, half a dozen authors showed that the coloration of F-centres in KCl takes place in two stages, the second one being responsible for non-linear behaviour. In this paper, we show that indeed in NaCl both F-centre and TL grow linear-supralinear-sublinearly with the dose during irradiation.